Naturally-occurring treefall gaps are an important part of forest ecology, playing a prominent role in the regeneration of both pioneer and non-pioneer tree species. Nate Lemoine is setting out to understand how insect herbivory plays a role in the growth and health of plants at treefall gaps. By caging small plots within gaps, he is deterring deer and other animals from eating the plants. He is also using herbicide to deter insects from some plots to compare to controlled plots where only water is sprayed.

Above-ground tree roots.

Peeking through the roots.

The sun peeping through to the gap. Treefall gaps provide unique conditions for plants including increased sunlight.

Intern Megan Palmer (Brown ’14) sprays plots with water.

Lemoine and Palmer walk past the treefall gaps during one of their regular spray sessions.

This caged plot has been receiving herbicide treatments and seems to be growing better than the plot where insect herbivory is occuring.

By Dejeanne Doublet, intern Conducting research with insects means that you must take on the roles and duties of a caretaker.

This summer we worked with the caterpillar species Spodoptera exigua (beet armyworms) and their close relative Spodoptera frugiperda(fall armyworms). Both species were shipped to us in sheets of eggs containing roughly 1,000 caterpillars. Most caterpillars start out their lives as eggs on leaves. They usually don’t get to pick and choose their food at the beginning of their lives, and are usually forced to eat from the plant or tree where they hatched.

Some caterpillars will enter a wandering stage once they’re big enough. They may wander about from plant to plant, picking and choosing what they like best or they may stay put at one type of plant for the rest of their life.

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When you’re a caterpillar shipped to a lab with 999 other caterpillars, though, you don’t necessarily get to have an all-you-can-buffet of cuisines. Our lab doesn’t quite function like a Subway and you can’t always have it your way. However, we do make sure you’re eating all your nutrients and vitamins with a homemade concoction of Lepidoptera food.

The recipe consists of more than a dozen ingredients that are simply mixed into boiling water. Click here for the full recipe. Once the ingredients are mixed together, they form a thick substance that cools down to form a tapioca pudding-like concoction.

We poured the finished food goo into 8 oz. plastic containers, allowed it to cool, then placed small pieces of the sheets containing caterpillars eggs on top of the food. We then placed the containers in a 30 ºC chamber under lights that mimic a 16-hour day and 8-hour night cycle. The caterpillars usually begin to hatch a day from when they arrive as eggs. Within a few days, they’re growing and eating and growing and eating.

Monarch caterpillars are not easy to come by. In the last five summers I’ve spent at the Smithsonian Environmental Research Center in Maryland, I’ve only come across several caterpillars per season. This year, our lab is full of monarch caterpillars with a count currently up to 13 caterpillars, three of which are forming their chrysalis shells and undergoing metamorphosis.

With the use of a microscope, we can photograph monarch caterpillars up close and personal. The monarch caterpillar (Danaus plexippus) in these photos was one of the first caterpillars we caught this season and is now being raised in our lab at the Smithsonian Environmental Research Center in Edgewater, MD. Photo by Dejeanne Doublet